update on biomarkers for the detection of endometriosis

Review ArticleUpdate on Biomarkers for the Detection of Endometriosis

Amelie Fassbender12 Richard O Burney3 Dorien F O12

Thomas DrsquoHooghe124 and Linda Giudice5

1Department of Development and Regeneration Organ Systems KU Leuven 3000 Leuven Belgium2Department of Obstetrics and Gynaecology Leuven University Fertility Centre University Hospital Leuven 3000 Leuven Belgium3Departments of Obstetrics and Gynecology and Clinical Investigation Madigan Healthcare System Tacoma WA 98431 USA4Division of Reproductive Biology Institute of Primate Research Karen Nairobi 00 100 Kenya5Department of Obstetrics and Gynecology University of California San Francisco San Francisco CA 94015 USA

Correspondence should be addressed toThomas DrsquoHooghe thomasdhoogheuzleuvenbeand Linda Giudice giudiceobgynucsfedu

Received 31 October 2014 Accepted 14 January 2015

Academic Editor Eric W-F Lam

Copyright copy 2015 Amelie Fassbender et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Endometriosis is histologically characterized by the displacement of endometrial tissue to extrauterine locations including thepelvic peritoneum ovaries and bowel An important cause of infertility and pelvic pain the individual and global socioeconomicburden of endometriosis is significant Laparoscopy remains the gold standard for the diagnosis of the condition However theinvasive nature of surgery coupled with the lack of a laboratory biomarker for the disease results in a mean latency of 7ndash11 yearsfrom onset of symptoms to definitive diagnosis Unfortunately the delay in diagnosis may have significant consequences in terms ofdisease progression The discovery of a sufficiently sensitive and specific biomarker for the nonsurgical detection of endometriosispromises earlier diagnosis and prevention of deleterious sequelae and represents a clear research priority In this review we describeand discuss the current status of biomarkers of endometriosis in plasma urine and endometrium

1 Background

Endometriosis is a debilitating gynecologic disease charac-terized by the implantation of endometrial tissue in ectopiclocations including the pelvic peritoneum ovaries andbowel The prevalence of endometriosis in reproductive agewomen is 2ndash10 [1] and as high as 35ndash50 in womenwith pain andor unexplained infertility [2] Endometriosisis a major cause of disability and significantly compromisedquality of life in women and adolescents [3] Symptomsinclude dysmenorrhea dyspareunia (pain with intercourse)lower abdominal andor back pain dyschezia (pain withbowelmovements) dysuria (painwith urination) and alteredbowel habits [4] Inflammation and innervation at sites ofendometriotic lesions are implicated as causes of pelvic pain[5 6] Endometriosis is a major cause of infertility due toinflammation-associated reductions in oocyte quality andendometrial receptivity to embryonic implantation [7] Aheritable component to endometriosis is well supported

though the specific genes involved remain an area of activeinvestigation The risk for first degree relatives of womenwith severe endometriosis is six times higher than forrelatives of unaffected women [8] and monozygotic twinstudies demonstrate high concordance rates not only forhistologically confirmed endometriosis but also for diseasestage [9]Though incomplete in accounting for the entirety ofreported clinicalmanifestations of the disease Sampsonrsquos the-ory of retrograde menstruation is the most widely accepteddescription of endometriosis pathogenesis [10] This theoryholds that endometriosis originates from the implantation ofsloughed endometrial tissue refluxed into the pelvis via thefallopian tube(s) during menstruation

Remarkably the gold standard for the diagnosis ofendometriosis remains direct visualization of lesions atsurgery preferably coupled with histologic confirmation ofendometrial glands and stroma in biopsies of suspectedlesions and this reality has significant consequences Asurgical diagnosis has multiple drawbacks compared to a

Hindawi Publishing CorporationBioMed Research InternationalVolume 2015 Article ID 130854 14 pageshttpdxdoiorg1011552015130854

2 BioMed Research International

minimally invasive diagnostic such as a blood or office-basedtest These include risks inherent to the procedure (organdamage hemorrhage infection and adhesion formation)as well as general anesthetic complications Also patientsneed to travel to a hospital or outpatient surgicenter withassociated financial costs to the patient and the healthcaresystem as well as prolonged time away fromwork and familyThe requirement for invasive surgery for the diagnosis ofperitoneal implants strongly contributes to an average latencyof 7ndash11 years from onset of symptoms to definitive diagnosis[3 11] This delay in diagnosis is due in part to presumptivetreatment of pain with oral contraceptives (OCPs) andnonsteroidal anti-inflammatory drugs (NSAIDs) as well asreluctance of physicians to refer women to gynecologists fordefinitive diagnosis reluctance of women to confront theirown pain for fear of a cancer diagnosis and dismissal of painespecially dysmenorrhea as a ldquonormalrdquo event [12] Delayeddiagnosis and treatment has significant consequences asendometriosis is more advanced in women whose diagnosticlaparoscopy is delayed supporting progression of diseaseover time [13] Indeed longitudinal placebo-controlled trialswith second look laparoscopy have demonstrated that 71ndash83 of untreated lesions will progress or remain stable overa 12-month period [14] At more advanced stages (stage III-IV of the revised American Fertility Society (rAFS) system)of endometriosis the severity of pelvic pain may lead tohysterectomy often with oophorectomy Endometriosis is thethird leading cause of hysterectomy in the United States [15]and increasing evidence exists for the malignant transforma-tion of ovarian endometriomas to ovarian cancer particularlythe clear cell and endometrioid subtypes [16]

In this review we describe and discuss the current statusof biomarkers of endometriosis in plasma urine and endo-metrium This review aims to encourage optimized studydesign data interpretation and validation considerations infuture biomarker development studies

2 Diagnostic Test for Endometriosis

Thegold standard for the diagnosis of peritoneal endometrio-sis has been visual inspection by laparoscopy followed byhistological confirmation [7] A noninvasive diagnostic testcould be developed for serum or plasma urine endometrialor menstrual fluid that can be recovered from the posteriorvaginal fornix and from the cervix during speculumexamina-tion [17 18] A semi-invasive test could be developed in peri-toneal fluid obtained after transvaginal ultrasound guidedaspiration or in endometrium obtained after transcervicalendometrial biopsy [17 18] The most important goal of thetest is that no women with endometriosis or other significantpelvic pathology are missed who might benefit from surgeryfor endometriosis-associated pain andor infertility [17ndash19]

To achieve this a test with a high sensitivity is neededwhich is the probability of a test being positive whenendometriosis is present At present such a test does not exist[17 20]

A noninvasive test for endometriosis would be use-ful for women with pelvic pain andor subfertility withnormal ultrasound This would include nearly all cases of

minimal-mild endometriosis some cases of moderate-severeendometriosis without clearly visible ovarian endometriomaand cases with pelvic adhesions andor other pelvic pathol-ogy who might benefit from surgery to improve pelvic painandor subfertility [17ndash19]

Although there is consensus in the World EndometriosisSociety that the development of a reliable noninvasive test isone of the top research priorities in endometriosis [11 21] thedevelopment of such a test from initial biomarker discoveryto a clinically approved biomarker assay is a long difficultand uncertain process [22] which can be classified in fourdifferent phases as described below [17 18]

Phase I (Preclinical Discovery Phase) This phase consists ofexploratory preclinical studies aiming to identify potentialbiomarkers In endometriosis research the state of the art inthis field has recently been reviewed by May et al [23]

Phase II (Retrospective Validation) This phase consists ofpreclinical assay development and validation of a clinicallyuseful noninvasive diagnostic test in the preclinical settingas has been done in the context of endometriosis in a recentpaper [24]

Phase III (Prospective Clinical Validation and Determinationof Clinical Utility)This phase establishes the diagnostic accu-racy and predictive value in the target population but thisphase has not yet been reached in endometriosis biomarkerresearch

Phase IV (Commercialization) Product development byindustry which has not yet been done successfully fornoninvasive endometriosis biomarkers

Overall most endometriosis biomarker studies haveremained at the level of Phase I [23] and only a few havemadeit to Phase II studies Clearly there is a need for well-designedPhase II and Phase III trials tomake progress in this field [18]A clinically reliable test for endometriosis can be expectedto have a profound impact on reduction of health care andindividual costs by [18]

(1) reducing time to diagnosis and the time wasted to seenumerous health care professionals

(2) subsequently reducing the time before individualizedspecialist care is invoked

(3) subsequently reducing expensive hit-and-miss treat-ments

(4) subsequently reducing expensive fertility treatmentsif the disease is under control before fertility isimpaired [25]

A worldwide study of costs caused by endometriosisindicates that the average annual total costs per woman are9579 euros of which 66 is caused by costs for productivityloss while medication counts for only 10 of the total yearlycosts [26] Furthermore endometriosis-associated symp-toms generated 0809 quality-adjusted life years per woman(the quality-adjusted life year is an outcome measure thataccounts for the quantity and quality of life and that allows for

BioMed Research International 3

comparison of outcomes between diseases) while the generalpopulation has 085ndash094 quality adjusted years per year [26ndash28] In summary a non- or semi-invasive test would notonly reduce the cost associated with endometriosis but alsoimprove the quality of life of women with endometriosis byallowing early diagnosis

3 Blood Biomarkers

Blood is an interesting potential source of biomarkers becauseit allows repeated measurements is easily obtained andis highly suitable for high-throughput measurements [29]Putative endometriosis biomarkers are mostly glycoproteinsgrowth or adhesion factors hormones or proteins related toimmunology or angiogenesis [17 23 30] Despite extensiveresearch no single biomarker nor a panel of biomarkers inperipheral blood has been validated as a diagnostic test forendometriosis [17 20]

Since the extensive review of May et al 2010 research inendometriosis biomarkers has accomplished the successfulvalidation of biomarkers in an independent sample dataset[24] but still no test for endometriosis is commerciallyavailable As described earlier different phases of biomarkerdiscovery exist (Phase IndashIV) and endometriosis biomarkersneed to be validated prospectively in a clinical setting [17]

31 Glycoproteins

311 Cancer Antigen- (CA-) 125 The use of CA-125 as bloodbiomarker for endometriosis has been examined extensively[23 24 30ndash36] Several studies have demonstrated theutility of CA-125 for the diagnosis of endometriosis andits correlation to disease severity especially endometrioticovarian cysts [23 32 33] However CA-125 is not specificfor endometriosis being a tumor marker elevated in ovariancancer [37 38] In addition to this lack of specificity thesensitivity to detect all endometriosis stages is low [31]According to a meta-analysis by Mol et al the sensitivity forstage IndashIV endometriosis was 50 and specificity was 72For stage III-IV endometriosis a sensitivity of 60 could beobtained with a specificity of 80 [31]

CA-125 has been measured simultaneously with uro-cortin [34] chlamydia antibody [35] CD23 [39] and inflam-matory cytokines [32] However none of these combinationsprovided a sufficiently high sensitivity or specificity forendometriosis and results remained unvalidated The com-bination of CA-125 CA-19-9 and survivin mRNA showedpromise boasting a sensitivity of 87 and a 10 false positiverate [33] A panel of CA-125 chemokine receptor (CCR) type-1 mRNA and monocyte chemoattractant protein- (MCP) 1showed a sensitivity of 922 and specificity of 816 to detectendometriosis [40] CA-125 combinedwith interleukin-8 (IL-8) and tumor necrosis factors-120572 (TNF-120572) in the secretoryphase had a sensitivity of 897 and specificity of 711 ina study performed by Mihalyi and coworkers [36] Ozhanet al stated that a panel consisting of CA-125 syntaxin-5and laminin-1 had 90 sensitivity 70 specificity and 887accuracy to distinguish endometriosis patients (119899 = 60) from

controls (119899 = 20) [41] However all these results remain to bevalidated

Another ovarian tumormarker CA-19-9 has been shownto be elevated in endometriosis and has a comparable or lowersensitivity than CA-125 for the detection of endometriosis[23] A recent study showed a significant increase of CA-125(119875 = 0001) CA-19-9 (119875 = 0015) and CA-15-3 (119875 = 0017)in endometriosis cases (119899 = 50) versus controls (119899 = 35) [42]ROC curve analysis showed that the area under the curve wasthe highest for CA-125 (0938) [42] For CA-19-9 a significantpositive correlation with disease severity was found [42]

Recently a panel of 4 biomarkers (CA-125 VEGF Annex-in V and glycodelinsoluble intercellular adhesion molecule(sICAM)-1) showed a sensitivity of 74ndash94 and a specificityof 55ndash75 in a training set and after initial validation in anindependent test set [24] These results should be prospec-tively evaluated

312 Other Glycoprotein Markers Follistatin an inhibitor ofactivin has been shown to be increased in endometriosispatients [23] especially in a subgroup of patients with ovarianendometrioma and showed good sensitivity and specificity[43] However a follow-up study could not reproduce theseresults [44] In a study conducted by Signorile and Baldi Zinc(Zn)-alpha2-glycoprotein was identified by mass spectrome-try (endometriosis cases 119899 = 5 controls 119899 = 5) as a possiblebiomarker for endometriosis and confirmed by ELISA to bedifferentially expressed (119875 = 0019) in an additional cohortof endometriosis patients (119899 = 120) and healthy controls(119899 = 20) [45] Reported sensitivity was 694 and specificitywas 100 [45]

Glycodelin A a promoter of neovascularization and cellproliferation was examined in follicular phase serum ofadolescent girls with endometriosis (119899 = 33) aged 13ndash19alongside TNF-120572 and IL-6 but none of these proteins showeda different expression compared with adolescents withoutendometriosis (119899 = 17) [46] A different study assessingglycodelin A found a significant increase in serum of womenwith endometrioma (119899 = 57) compared with control womenundergoing sterilization or having benign ovarian cysts (119899 =42) and demonstrated the potential use of glycodelin A asa biomarker for ovarian endometriosis with a sensitivity of821 and a sensitivity of 784 [47] Glycodelinwas includedin a biomarker panel proposed by Vodolazkaia et al forthe diagnosis of ultrasound-negative endometriosis [24] asmentioned in the section above on ldquoGlycoproteinsrsquorsquo

32 Immunological Markers and Inflammatory CytokinesInflammatory and immunological markers have been impli-cated in the pathogenesis of endometriosis and have beenexamined extensively as possible biomarkers for endometrio-sis [23] A plethora of cytokines has been assessed in thesearch for a noninvasive diagnosis of endometriosis includ-ing IL-1 IL-6 IL-8 TNF-120572 MCP-1 and interferon-120574 (IFN-120574)[23] In a study by Panoulis et al no difference in the serumexpression of the inflammatory markers CD40 CD40L and adisintegrin and metalloproteinase domain 8 (ADAM8) wasdetected between endometriosis patients (119899 = 47) andcontrols (119899 = 29) [48] Values of T-helper pathway related


interleukins IL-10 IL-12 IL-17 and IL-23 levels were compa-rable between infertile controls and endometriosis patientswith infertility [49] Contrasting results regarding changesin the complement system and soluble histocompatibilityantigen (HLA) have been recorded [23] The inflammatorymarker C-reactive protein (CRP) has been shown to beupregulated [23] especially when examined with a highsensitivity assay making it possible to detect subclinicalinflammation in women with endometriosis [50] Howeverother studies could not find an upregulation [23 51] Sig-nificantly increased IL-4 serum values have been found inadolescents with endometriosis [52] In a recent study theinflammatorymarker co-peptin was significantly (119875 = 0002)higher in women with endometriosis (119899 = 50) than inwomen without endometriosis (119899 = 36) and was positivelycorrelated with disease severity [42] At a cut-off value of25118 pgmL its sensitivity to predict endometriosis was 65and the specificity was 583 [42] In a study by the samegroup the inflammatory biomarker YKL-40 was significantlyelevated (119875 lt 0001) in patients with endometriosis (119899 = 53)compared with patients without endometriosis (119899 = 35)and a positive correlation with disease severity was detected[53] A study by Mihalyi et al found a panel consisting ofluteal plasma levels of IL-8 TNF-120572 and CA-125 that was ableto distinguish between 201 women with endometriosis and93 controls with a normal pelvis with a sensitivity of 897and a specificity of 711 [36] In a study by Vodolazkaiaet al univariate analysis showed the differential expressionof several cytokines and chemokines in 232 women withendometriosis and 121 controls [24] However no cytokinesor chemokines were included in the final proposed panelof biomarkers after multivariate analysis [24] Recently theputative use of chemokines as biomarkers of endometriosishas been reviewed by Borrelli et al [54] In peripheralblood IL-8 MCP-1 and RANTES showed potential as abiomarker being significantly increased in endometriosiscases versus controls in respectively 461 50 and 75of the assessed studies [54] However no consensus exists onwhether cytokines are suitable to discriminate endometriosispatients from patients with other pelvic pathology [24]

33 Oxidative Stress Women with endometriosis mightexperience increased oxidative stress in the pelvic cavity dueto the retrograde flow of menstrual erythrocytes that releaseiron upon rupture [55]This has been confirmed by a numberof groups that found alterations in a range of proteins relatedto oxidative stress A significant reduction in serum has beenreported for paroxonase (PON-I) high density lipoproteins[56] and plasma superoxide dismutase [57] and an increaseof total cholesterol triglycerides low-density lipoproteinlipid peroxidises [56] 25-hydroxycholesterol [58] heat shockprotein 70b1015840 (HSP70b1015840) [59] and Vitamin E [57]

34 Cell Adhesion and Invasion Levels of the sICAM-I havebeen suggested to rise during early stages of endometriosis(I-II) and decrease at stage III-IV [23] CorrespondinglysICAM-I has been included in a panel with three othermarkers to diagnose endometriosis cases that could notbe identified by preoperative ultrasound [24] In addition

the cell adhesion molecule osteopontin was elevated inplasma for all disease stages [60 61]

After initial cell adhesion invasion of endometrial tissuefragments into the peritoneum may be facilitated throughremodeling of the extracellular matrix by matrix metallopro-teinases (MMPs) [62] MMP-2 [63] and MMP-9 [64] havebeen found to be significantly increased in endometriosispatients versus controls Moreover advanced endometriosisis correlated with a higher MMP-2 expression [65] In astudy by de Sanctis et al mRNA levels of MMP-3 weresignificantly higher in stage IIndashIV endometriosis cases than incontrols [66]The same study showed similar levels of MMP-9 and vascular endothelial growth factor A (VEGF-A)mRNAamong cases and controls [66]

35 Angiogenesis VEGF is an important regulator of angio-genesis Its usefulness as biomarker for endometriosis isunclear as some studies show elevated blood levels inendometriosis patients while other studies do not record asignificant difference [23 67] Follow-up of patients withadvanced endometriosis showed reducedVEGF-A levels afterlaparoscopic excision of the lesions [68 69] In anotherstudy danazol treatment of endometriosis patients resultedin an increased VEGF concentration in plasma [70] Despitethese contrasting results a recent study proposing a panelof biomarkers included VEGF in two panels to detect min-imalmild endometriosis with 80 sensitivity [24]

Pigment epithelium-derived factor (PEDF) is an inhibitorof angiogenesis and has neurotrophic and anti-inflammatoryproperties [71] In a study by Chen et al PEDF was signif-icantly decreased in women with endometriosis (119899 = 43)compared with women without endometriosis (119899 = 28)independent of the phase of the cycle and correlated withpain symptoms [71] Other growth factors such as solubleepidermal growth factor (EGF) and platelet-derived growthfactor (PDGF) have been investigated but no difference wasfound between endometriosis patients and control women[23] Hepatocyte growth factor (HGF) was suggested to beelevated in women with endometriosis [72] although thiswas not confirmed in an additional study [23 73] Theserum concentration of its receptor c-Met was significantlyhigher in endometriosis patients (119899 = 130) than in controls(119899 = 39) in a stage dependent manner [74] Elevations offibroblast growth factor-2 (FGF-2) angiogenin and solubleFlt-I (VEGFR-1) in serum of womenwith endometriosis haveall been recorded [23]

36 Hormones Contrasting evidence exists on prolactinleptin luteinizing hormone (LH) and adiponectin levels inendometriosis patients versus controls showing either nodifference an increase (prolactin leptin LH) or a decrease(adiponectin) [23 75 76] No consensus exists on changes insteroid hormone levels [23]

37 Autoantibodies Both total immunoglobulin levels andantiendometrial antibodies have been investigated as poten-tial biomarkers for endometriosis of which the latter showedthe most promising results being more commonly present


in endometriosis patients than in controls [23] Like-wise specific antibodies against carbonic anhydrase trans-ferrin 1205722-HS glycoprotein lipid peroxide modified rab-bit serum albumin copper oxidized low-density lipopro-tein and malondialdehyde-modified low-density lipoproteinlaminin-I and cardiolipin have shown promise as potentialendometriosis biomarkers [23] Additionally serum anti-PDIK1L [77] and anti-syntaxin 5 autoantibodies [78] werereported elevated in endometriosis patients In patients withovarian endometrioma autoantibodies against Insulin-likegrowth factor 2mRNA-binding protein 1 (IMP1) were signifi-cantly higher than in healthy controls [79] In a study byGajb-hiye et al 40 endometriosis patients were compared with30 controls [80] Autoantibodies against different epitopes oftropomyosin 3 (TPM3) stomatin-like protein 2 (SLP2) andtropomodulin 3 (TMOD3) were significantly elevated in theserumof endometriosis patients with bothminimalmild andmoderatesevere disease [80]

38 miRNA Micro RNAs (miRNAs) are highly conservedshort noncoding sequences that regulate gene expressionat the posttranscriptional level Generally miRNAs represstranscription of their targeted messenger RNAs With over2200 distinct miRNAs identified to date miRNA regulatorymechanisms are redundant overlapping and complex [81]For example most miRNA are able to regulate several hun-dred transcripts and several miRNA often regulate the samemRNA target [82] Functional studies are increasingly clarify-ing the regulatory roles of individual miRNAs The reducedproclivity of miRNA to degradation relative to mRNA [83]and strong correlation between tissue and serum miRNAexpression evidenced in other disorders [84] are favorablefeatures of miRNA in the context of biomarker potential

Recently miRNAs in peripheral blood have been sug-gested as potential endometriosis biomarkers as reviewed byFassbender et al [85] Reduced plasma levels of miR-17-5pmiR-20a andmiR-22 [86] and elevated plasma levels of miR-16miR-191 andmiR-195 [87] have been found inwomenwithendometriosis compared with women without endometrio-sis A study evaluating serum miRNA levels found anelevation of miR-199a and miR-122 and a decrease of miR-145lowast miR-141lowast miR-542-3p and miR-9lowast in endometriosispatients compared with controls [88]

39 Proteomics A variety of studies has been publishedregarding protein ldquofingerprintsrdquo for the diagnosis ofendometriosis [23 89ndash91] A proteomic fingerprint modelbased on three peptide peaks had 914 sensitivity and95 specificity to detect endometriosis when comparing126 patients with endometriosis with 120 healthy controls[90] Furthermore this combination of peptide peaks wasvalidated in an independent cohort showing a sensitivityof 893 and a specificity of 90 [90] A combinationof 5 peptide peaks discovered by surface-enhanced laserdesorptionionization time-of-flight (SELDI-TOF) massspectrometry detected endometriosis with a sensitivityof 88 and a specificity of 84 in the menstrual phase[91] These studies have shown promising results howeverproteomics technologies are costly and time-consuming

[23] and there is a need for better standardization andreproducibility of proteomic technologies before they can beused reliably in clinical research projects [17]

310 Metabolomics Additionally studies regarding themetabolome of endometriosis patients have been executedStearic acid was significantly reduced (119875 = 0030) inendometriosis patients (119899 = 64) compared with controls(119899 = 74) [92] In a study comprising patients with ovar-ian endometriosis (119899 = 40) eight metabolites and 81metabolite ratios were significantly higher in the endometri-osis group compared with healthy controls undergoing lapa-roscopy for sterilization (119899 = 52) [93] The combinationof hydroxysphingomyelin C161 and the ratio betweenphosphatidylcholine C362 to ether-phospholipid C342adjusted for the effect of age and BMI provided a sensitivityof 900 and a specificity of 843 for the detection ofendometriosis [93] A study comprising 22 women withmin-imalmild endometriosis and 23 controls found highervalues of Lactate 3-Hydroxybutyrate L-Alanine Glycero-phosphatidylcholine L-Valine L-Leucine L-Threonine2-Hydroxybutyrate L-Lysine Succinic acid in the endomet-riosis group and lower values of Glucose L-Isoleucine andL-Arginine [94] More research on the differences in themetabonomic profile between women with and withoutendometriosis should determine whether it could serve as anoninvasive diagnosis of endometriosis

311 Circulating Cell-Free DNA In a study by Zachariahet al the concentration of circulating cell-free nuclear DNAwas higher in endometriosis patients compared with thecontrol group (119875 = 0046) leading to the conclusion thatcirculating cell-free DNA may be a potential biomarker forendometriosis [95] However this assumption needs furtherinvestigation

312 Cell Populations A range of cell populations includ-ing T cells B cells natural killer (NK) cells macropha-gesmonocytes and polymorphonuclear neutrophils hasbeen compared between endometriosis patients and healthycontrols [23] However for none of these populations theutility as an endometriosis biomarker has been proven[23 96] Recently a CD25high forkhead box 3+ (FOXP3+)subset of CD4+ regulatory T cells has been shown to bedecreased in peripheral blood of women with endometrioma(119899 = 17) compared with healthy controls (119899 = 15) [97]Additionally the potential use of circulating angiogenic cellsas biomarkers for endometriosis has been examined but nodifference between endometriosis patients and controls couldbe detected [98]

4 Urine Biomarkers

For many diseases urine has become among the most widelyused clinical sample for biomarker discovery due to easeof access and less complex fluid composition However inendometriosis biomarker development urine as an approachis significantly less targeted relative to blood Since 2010 only


11 of reported endometriosis biomarker studies were urine-based [99]

Like serum urine reflects an amalgam of systemic pro-cesses Analysis of pooled urine from healthy men andwomen revealed that 70 of the urine proteins originatedirectly from the urinary system and the remaining 30represent proteins from other organ systems filtered by thekidney [100] Though legitimizing urine as a diagnosticmedium this finding also suggests potential for reducedspecificity and it will be important to assess the ability ofa urinary assay to differentiate endometriosis from otherinflammatory conditions

Urine-based biomarker candidates measured by a vari-ety of protein detection methods have been reported sin-gularly or combined in a panel of markers Creatinine-corrected soluble fms-like tyrosine kinase (sFlt-1) was foundto be significantly elevated in the urine of women withendometriosis using enzyme-linked immunosorbent assays(ELISA) [101] Using an immunoblot technique Tokushigeet al demonstrated cytokeratin-19 (CK19) to be uniquelyexpressed in 11 urine samples fromwomenwith histologicallyproven endometriosis relative to samples from 6 womenfree of disease [102] A larger prospective study was sub-sequently unable to confirm the diagnostic potential forurinary CK19 [103] possibly due to different specimen col-lection techniques or different subject characteristics As inserum matrix metalloproteinases (MMPs) have been inves-tigated for association with endometriosis A panel consist-ing of MMP-2 MMP-9 and MMP-9neutrophil gealtinase-associated lipocalinwas significantly elevated in a cohort of 33women with endometriosis relative to expression in a groupof 13 controls [104]

Relative to blood urine evidences a significantly nar-rower dynamic range of proteins thereby allowing morerapid preparation of specimens for proteomic interrogationAdditionally the urine proteome is relatively stable for upto six hours at room temperature and for over 17 yearsstored at minus70∘C [105] Using matrix assisted laser desorp-tionionisation time-of-flight mass spectrometry (MALDI-TOF MS) several groups have reported differential peptideprofiles in the urine of women with endometriosis relative tothat of women without endometriosis at surgery [102 106]El-Kasti et al identified a 32809Da periovulatory peptidethat differentiated all stages of endometriosis from controlswith 82 senstitivity and 88 specificity Tokushige et alcoupledMALDI-TOF with two-dimensional polyacrylamidegel electrophoresis (2D-PAGE) to reveal 12-fold higherexpression of five proteins in affected women ImportantlyMALDI-TOF does not allow direct identification of peptidesor proteins that are differentially synthesized or secretedwhich is fundamental to further validation and clinical assaydevelopment although protein pattern recognition holdspromise for the future

Advances in mass spectrometry (MS) technologies andbioinformatics have enabled protein analysis that can identifyqualitative and quantitative differences in large numbersof lower abundance proteins Cho et al used 2D-PAGEand tandem MS to identify significantly higher levels of 22

urine proteins in women with endometriosis including vita-min D-binding protein prealbumin enolase-1 and alpha1-antitrypsin [107] As individual analytes these proteins evi-denced insufficient sensitivity and specificity for use as abiomarker Despite elevation in women with endometriosisenolase-1 lacked sufficient diagnostic power as an individualanalyte (sensitivity 56 and specificity 72) in a separatestudy [108]

5 Endometrial Biomarkers

Though more invasive than serology endometrial tissueis accessible via biopsy in the office setting and offersthe potential advantage of improved specificity Devicessuch as the Pipelle suction-based sampler are commonlyused in the office without the need for anesthesia Theendometrium presents several unique characteristics withrespect to biomarker discovery First the endometriumevidences remarkable sex steroid-driven cyclic variationand regenerative capacity Whole genome profiling of nor-mal endometrium revealed tremendous molecular variationbetween samples taken from the proliferative early-secretorymidsecretory and late-secretory phases of the menstrualcycle [109] and this basal cyclic variation in the endometriummust be accounted for in the interpretation of endometrialgene and protein expression signatures An endometrialdiagnostic assay is preferably obtained in the proliferativephase as this avoids concerns regarding interruption of anascent unanticipated pregnancy

In addition to menstrual cycle phase gynecologic con-ditions other than endometriosis have been shown to influ-ence eutopic endometrial gene and protein expression Theendometrial transcriptome in women with endometriosismay have shared patterns of dysregulation with other inflam-matory conditions such as hydrosalpinx [110] or other estro-gen dependent diseases such as leiomyomata endometrialpolyps or adenomyosis [111 112] Clustered pathologies mayconfound the interpretation of molecular measurements inthe delineation of a biomarker unique to endometriosis Con-sequently screening and annotation of coexisting pathologyis an important consideration in the biomarker discoveryand validation process A systematic review of over 200potential endometrial biomarkers including hormones andtheir receptors (119899 = 29) cytokines (119899 = 25) factorsidentified through proteomics (119899 = 8) and histology (119899 =10) revealed sensitivity and specificity (reported in only 32articles) ranging from 0 to 100 [113]

51 Endometrial Transcriptome At the transcript level sig-nificant differences in gene expression exist in eutopicendometrium fromwomen with versus without endometrio-sis [114ndash117] Both array-based global and targeted geneexpression studies [113] have identified genes and pathwaysthat may be involved in disease pathogenesis and revealpotential candidates for the development of an endometrial-based biomarker Recently whole genome microarray datainvolving 144 endometrial specimens from women withendometriosis or other benign gynecologic pathology (ieleiomyomata endometrial polyp and hydrosalpinx) and


fromwomen with surgically confirmed normal findings wereused to developmenstrual cycle phase specific classifiers withhigh accuracy in the detection of both endometriosis andstage of disease [118] In each cycle phase specimens werepartitioned into 80 construction and 20 independentvalidation sets for margin tree based training and testing ofclassifiers Interestingly relatively few genes were required todelineate endometriosis from other benign pelvic conditionsand to classify disease severity For example the two bestperforming proliferative and early-secretory phase-specificdisease classifiers achieved 100 accuracy using less than 100genes for each disease classification decision These highlyinformative gene sets provide a finite panel for biomarkerdevelopment purposes The delineation of endometriosisfrom other benign pelvic conditions represents an importantstrength of this study considering the high rate of clustering ofestrogen dependent pathologies Prospective validation in alarge independent cohort of endometrial specimens collectedat multiple centers is warranted

52 MicroRNAs MicroRNAs (miRNAs) evidence differen-tial expression in the endometrium of women with versuswithout endometriosis and therefore offer potential as anendometriosis biomarker

Like the endometrial transcriptome generally microRNAexpression in normal endometrium exhibits dynamicchanges across the menstrual cycle A comparison of miRNAarray based profiles of human primary epithelial cellsisolated from estrogen-dominant late proliferative (119899 = 4)and progesterone-dominant mid secretory (119899 = 4) phaseendometrial specimens identified 24 differentially expressedmiRNAs [119] This finding highlights both the prospect formiRNA dysregulation in the pathogenesis of endometrialdisorders and the importance of accounting for menstrualcycle phase in the interpretation of miRNA profiles inbiomarker discovery protocols

Global differential expression of miRNAs in eutopiccompared with ectopic endometrium has been evaluatedby several groups [120ndash124] Pan et al identified differ-ential expression of 48 miRNAs in a microarray analysisof early to mid-secretory eutopic endometrial tissues fromendometriosis-free volunteers (119899 = 4) and from eutopic(119899 = 4) and ectopic (119899 = 8) endometrial tissues from womenwith endometriosis Using arrays probing 377 miRNAs tocompare eutopic and ectopic (peritoneal) endometrium fromseven women with stage IIndashIV endometriosis Teague et aldetected dysregulation of 22miRNAs with predicted cognatemRNA targets known to be involved in endometriosis patho-genesis [121] Interestingly the dysregulation of miRNAs wascycle phase independent though the relatively small samplesize limited definitive correlation Similar to peritoneal dis-ease ovarian endometriosis evidenced differential expressionof miRNAs relative to paired eutopic endometrium in severalstudies [122 123] A more recent study revealed 156 miRNAsdifferentially expressed between endometriotic tissue andnormal endometrium including twelvemiRNAs known to beinvolved in fibrinolysis and angiogenesis [124] These studieshighlight molecular pathways that may be associated withthe development of endometriosis as well as the changes

in expression signature that exist in ectopically locatedendometrial tissue

In contrast to studies comparing miRNA expression ineutopic versus ectopic endometrium relatively few studieshave compared miRNA expression in eutopic endometriumfrom women with and without surgically confirmedendometriosis [120 125 126] In a parallel miRNA-mRNAarray based comparison of three control early secretory phaseendometrium (119899 = 3) with endometria from four womenwith moderate-severe endometriosis six downregulatedendometriosis associated miRNA were identified from themiR-9 and miR-34 miRNA families [125] MiR-9 is alsodysregulated in endometrioid ovarian cancer with whichendometriosis is associated Though strengthened by thestringency of including only surgically documented presenceor absence of advanced stage endometriosis the study islimited by inclusion of control endometrium from womenwith coexisting intramural leiomyomata which couldconfound delineation of endometriosis-specific miRNAdifferences This group further compared miRNA expressionin women with mild and severe endometriosis and foundincreased endometrial expression of miR-21 and DICER inthe more advanced stage of the disease [126] In additionto these global miRNA studies others have comparedendometrial expression of individual miRNAs in the eutopicendometrium of women with and without endometriosisIn general individual miRNAs are selected on the basis ofbiological plausibility in the pathogenesis of the disorderFor example miR-135a (proliferative phase) and miR-135b(proliferative and secretory phases) were investigated due totheir predicted interaction with Homeobox protein (HOX)A10 [127] The overexpression of these miRNAs correlatedwith the downregulation of HOXA10 in endometrium fromwomen with endometriosis Direct regulation of HOXA10by miR-135ab was subsequently confirmed by luciferaseassay in cultured endometrial stromal cells Other miRNAsand predicted cognate mRNAs demonstrating differentialexpression in eutopic endometrium from women with andwithout endometriosis include miR-23aCYP19A1 and miR-542-3pCOX2 [128] miR-126CRK [129] andmiR23aNR5A1[130] Notably the reports of miR-23a expression in eutopicendometrium from women with and without endometriosisshowed opposite directions of dysregulation with one studyinvolving proliferative endometrial specimens and the otherincluding only early to midsecretory samples

The demonstration of aberrant microRNA expressionprofiles in the eutopic endometrium from women withendometriosis may yield promising biomarker targets How-ever independent validation and replication of miRNA dys-regulation in phase specific comparisons are needed To datethe utility of miRNAs as biomarkers for endometriosis hasnot been specifically tested

53 Endometrial Proteome Several groups have reportedunique proteomic profiles using the SELDI-TOFMSplatformin eutopic endometrial specimens from women with andwithout endometriosis [131 132] Importantly the SELDI-TOF MS methodology provides differential proteomic pro-files in the form of masscharge (mz) peaks without


attendant characterization of the peptides or proteins In2006 the first of these reports described reduced expressionof a protein peak in secretory phase endometrium fromwomen with mild endometriosis relative to controls [133] Alarger study identified differential expression of 32 peptidepeaks in secretory phase endometrium from 10 women withendometriosis (all rAFS stages) compared to that of 6 healthywomen [134] Wang et al performed proteomic profiling ofendometrium from 13 women with and 13 women withoutendometriosis identifying five differentially expressed pep-tide peaks (5385 mz 5425 mz 5891 mz 6448 mz and6898 mz) that collectively showed 917 sensitivity and90 specificity in the diagnosis of endometriosis [132] Inthe largest study to date involving a total of 53 endometrialsamples a panel of three differentially expressed peptidepeaks (16069 mz 15334 mz and 15128 mz) diagnosedendometriosis (all rAFS stages) with 875 sensitivity and862 specificity [135] Another study characterized a panelof five differentially expressed peptide peaks in secretoryphase endometrium (1949 mz 5183 mz 8650 mz 8659mz and 13910 mz) to have 895 sensitivity and 90specificity for the diagnosis of any stage endometriosis [136]In a unique concomitant assessment of the endometrialtranscriptome and proteome Fassbender et al described apanel of differentially expressed peptide peaks (2072 mz2973 mz 3623 mz 3680 mz and 21133 mz) in the earlysecretory endometrial proteome of women with versus with-out endometriosis as diagnostic of endometriosis (all rAFSstages) with 91 sensitivity and 80 specificity [131] Thoughthe differentially expressed mz peaks identified amongseparate groups showed no overlap important methodolog-ical differences are apparent Specifically menstrual cyclephase of endometrial samples was not specified in severalof the studies [132 135] and only one randomly dividedendometrial samples into training and test sets [131] Todate none of the differentially expressed peptide peaks havebeen validated in an independent study cohort to whichinvestigators are blinded as to patientsrsquo disease status Ofparamount importance toward the development of a clinicallaboratory protein assay such as ELISA is the identification ofdifferentially expressed peptides and proteins

54 Neuronal Marker Clarification of the role of neuroan-giogenesis in endometriosis has led to investigation of thebiomarker potential for nerve fibers in eutopic endome-trial samples Nerve fibers were first detected in peritonealendometriotic lesions and these were thought to contributeto associated dysmenorrhea [137] Immunohistochemicaldetection of the protein gene product 95 (PGP95) a highlyspecific pan-neuronal marker was described at peritoneallesions developing from surgically transplanted uterine hornsegments in a rat model of endometriosis [138] Thesefindings in endometriotic lesions led to assessment fordifferences in nerve fiber density in the eutopic endometrialmicroenvironment In a study of sharp curettage and fullthickness hysterectomy specimens PGP95 immunostainednerve fibers were detected in the functional endometrial layerfrom all women with surgically confirmed endometriosis butnone of the specimens from unaffected controls and this

finding was cycle phase independent [139] These strikingfindings were followed by two independent studies assessingthe detection of endometrial nerve fibers as a diagnostictest for endometriosis [140 141] In a study of archivedbiospecimens the density of nerve fibers was fourteen timeshigher in the endometrium of women with rAFS stage I-II endometriosis relative to that of healthy women and thecombination of PGP95 substance P and vasoactive intestinalpeptide was 95 sensitive and 100 specific for the diagnosisof endometriosis [141] In a double blind study of endometrialpipelle samples from 99 consecutive women undergoinglaparoscopy for pelvic pain andor infertility immunohisto-chemical detection of PGP95 demonstrated 98 sensitivityand 83 specificity for the finding of endometriosis atsurgery [140] Importantly nerve fibers were not observed inother benign gynecologic conditions to include endometri-tis leiomyomata or endometrial polyps Meticulous sam-pling technique for collection and proper orientation of thefunctional endometrial layer were methodologic points ofemphasis These results were confirmed in a study of 27prospectively collected eutopic endometrial specimens usingidentical sampling and detection methods [142] Howeverthe adoption of this method in a clinical laboratory failed torecapitulate the accuracy of endometrial PGP95 immunohis-tochemistry in the diagnosis of women with endometriosis[143] Functional endometrial layer nerve fibers assessed byPGP95 immunostaining were detected in 9 of 45 (22)of histologically confirmed cases of endometriosis and in6 of 21 (29) of women without endometriosis Potentialexplanations for the discrepant results include curette ratherthan pipelle-based sampling inability to orient the curettefragments for functional layer assessment and inclusionof women undergoing hormonal treatment Nonethelessthe detection of nerve fibers in 29 of women withoutendometriosis raised concerns regarding the assayrsquos speci-ficity [143] The specificity of endometrial nerve fiber densitywas further challenged by the finding of similar endometrialinnervation and neuronal growth fibers in women withadenomyosis with expression reported to be more correlatedwith pelvic pain than diagnosis [144] Studies involving largerpopulations are needed to validate the utility of endometrialnerve fiber density as a biomarker for endometriosis

6 Standard Operating Procedures

Many centres worldwide have been collecting blood or otherbody fluids such as peritoneal fluid endometrial fluid andmenstrual fluid as well as tissue samplesmdashin particularectopic and eutopic endometriummdashfrom women with andwithout endometriosis for a variety of research purposes[145ndash147] The adoption of validated internationally agreedupon standard operating procedures (SOPs) for tissue samplecollection processing and storage and standardized pheno-typic and other patient data collection are crucial to optimisesample quality reduce variability and enable cross-centrestudies [17 113 148] This can allow researchers to overcomethe main pitfalls in the study design and methodology suchas small sample size lack of relevant clinical informationinconsistency in sample handling and storage and technical


control of preanalytical sample variability which contributeto controversial study results in endometriosis research [17]

Recently the World Endometriosis Research Foundation(WERF) Endometriosis Phenome and BiobankingHarmoni-sation Project (EPHect) has developed a consensus onstandardisation and harmonisation of phenotypic surgicalclinical data and biologic sample collection methods inendometriosis research [146 147 149 150] This consensus[146 147 149 150] was developed on the basis of publiclyavailable SOPs fromgeneral large-scale biobanking efforts ona systematic literature search in PubMed and Google searchon published SOPs for endometriosis related biobanking[17 151] and on personal biobank experience from studyparticipants Two types of SOPs were developed standardrecommended andminimum required ldquoStandardrsquorsquo collectionSOPs should be adopted where possible as they will yieldresults that are least prone to variation and degradationof the samples ldquominimumrdquo SOPs should be used by allindividuals starting an endometriosis biobank as they providethe fundamentals for standardization required as an absoluteminimum requirement given unavoidable logistical and bud-getary circumstances All questionnaires and SOPs producedby the WERF EPHect Working Group are freely availablefor use by investigators on the WERF EPHect websitehttpendometriosisfoundationorgephect [146 147 149150]

7 Conclusion

Despite the plethora of studies on endometriosis biomarkersneither a single biomarker nor a panel of biomarkers hasbeen validated for a noninvasive diagnostic testwith sufficientsensitivity and specificity [17] A first step toward validation ofbiomarkers has beenmade [24 140] however further studiesare needed to develop a clinically useful test Currentlybiomarker research in endometriosis is still lacking repro-ducible data with high sensitivity and specificity In additionlimitations derive from small sample size and suboptimalcharacterisation of specimens (no breakdown according tomenstrual phase or lesion phenotype)

Discovery of new biomarkers and validation of putativebiomarkers are crucial to make progress in the field [17]and are top research priorities for endometriosis proposed in2009 and 2013 by highly ranked researchers [11 21]

Disclosure

Amelie Fassbender and Richard O Burney are joint firstauthors Thomas DrsquoHooghe and Linda Giudice are joint lastauthors

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] L C Giudice ldquoClinical practice EndometriosisrdquoThe New Eng-land Journal of Medicine vol 362 no 25 pp 2389ndash2398 2010

[2] B Eskenazi and M L Warner ldquoEpidemiology of endometrio-sisrdquoObstetrics and Gynecology Clinics of North America vol 24no 2 pp 235ndash258 1997

[3] K E Nnoaham L Hummelshoj P Webster et al ldquoImpactof endometriosis on quality of life and work productivity amulticenter study across ten countriesrdquo Fertility and Sterilityvol 96 no 2 pp 366e8ndash373e8 2011

[4] T DrsquoHooghe and L Hummelshoj ldquoMulti-disciplinary cen-tresnetworks of excellence for endometriosis management andresearch a proposalrdquo Human Reproduction vol 21 no 11 pp2743ndash2748 2006

[5] K J Berkley A J Rapkin and R E Papka ldquoThe pains ofendometriosisrdquo Science vol 308 no 5728 pp 1587ndash1589 2005

[6] N Tokushige R Markham P Russell and I S Fraser ldquoNervefibres in peritoneal endometriosisrdquo Human Reproduction vol21 no 11 pp 3001ndash3007 2006

[7] L C Giudice and L C Kao ldquoEndometriosisrdquo The Lancet vol364 no 9447 pp 1789ndash1799 2004

[8] J L Simpson S Elias L R Malinak and V C Buttram JrldquoHeritable aspects of endometriosis I Genetic studiesrdquo TheAmerican Journal of Obstetrics and Gynecology vol 137 no 3pp 327ndash331 1980

[9] R M Hadfield P L Yudkin C L Coe et al ldquoRisk factors forendometriosis in the rhesus monkey (Macaca mulatta) a case-control studyrdquo Human Reproduction Update vol 3 no 2 pp109ndash115 1997

[10] J A Sampson ldquoPeritoneal endometriosis due to menstrualdissemination of endometrial tissue into the peritoneal cavityrdquoAmerican Journal of Obstetrics amp Gynecology vol 14 pp 442ndash469 1927

[11] P A W Rogers T M DrsquoHooghe A Fazleabas et al ldquoDefiningfuture directions for endometriosis research workshop reportfrom the 2011World Congress of Endometriosis inMontpellierFrancerdquo Reproductive Sciences vol 20 no 5 pp 483ndash499 2013

[12] K Ballard K Lowton and J Wright ldquoWhatrsquos the delay Aqualitative study of womenrsquos experiences of reaching a diagnosisof endometriosisrdquo Fertility and Sterility vol 86 no 5 pp 1296ndash1301 2006

[13] T M DrsquoHooghe and S Debrock ldquoEndometriosis retrogrademenstruation and peritoneal inflammation in women and inbaboonsrdquoHuman Reproduction Update vol 8 no 1 pp 84ndash882002

[14] C J G Sutton S P Ewen N Whitelaw and P Haines ldquoPro-spective randomized double-blind controlled trial of laserlaparoscopy in the treatment of pelvic pain associated withminimal mild and moderate endometriosisrdquo Fertility andSterility vol 62 no 4 pp 696ndash700 1994

[15] D L Clarke-Pearson and E J Geller ldquoComplications of hys-terectomyrdquo Obstetrics and Gynecology vol 121 no 3 pp 654ndash673 2013

[16] C L Pearce C Templeman M A Rossing et al ldquoAssociationbetween endometriosis and risk of histological subtypes ofovarian cancer a pooled analysis of case-control studiesrdquo TheLancet Oncology vol 13 no 4 pp 385ndash394 2012

[17] A Fassbender A Vodolazkaia P Saunders et al ldquoBiomarkersof endometriosisrdquo Fertility and Sterility vol 99 no 4 pp 1135ndash1145 2013


[18] A Fassbender O Dorien B de Moor et al ldquoBiomarkers ofendometriosisrdquo in Endometriosis Pathogenesis and TreatmentT E Harada Ed pp 321ndash339 Springer Berlin Germany 2014

[19] T M DrsquoHooghe A M Mihalyi P Simsa et al ldquoWhy we need anoninvasive diagnostic test for minimal to mild endometriosiswith a high sensitivityrdquo Gynecologic and Obstetric Investigationvol 62 no 3 pp 136ndash138 2006

[20] K E May S A Conduit-Hulbert J Villar S Kirtley S HKennedy and C M Becker ldquoPeripheral biomarkers of endo-metriosis a systematic reviewrdquo Human Reproduction Updatevol 16 no 6 pp 651ndash674 2010

[21] P A Rogers T M DrsquoHooghe A Fazleabas et al ldquoPrioritiesfor endometriosis research recommendations from an interna-tional consensus workshoprdquo Reproductive Sciences vol 16 no4 pp 335ndash346 2009

[22] S Surinova R Schiess R Huttenhain F Cerciello B Woll-scheid and R Aebersold ldquoOn the development of plasmaprotein biomarkersrdquo Journal of Proteome Research vol 10 no1 pp 5ndash16 2011

[23] K E May S A Conduit-Hulbert J Villar S Kirtley S HKennedy and C M Becker ldquoPeripheral biomarkers of endo-metriosis a systematic reviewrdquo Human Reproduction Updatevol 16 no 6 Article ID dmq009 pp 651ndash674 2010

[24] A Vodolazkaia Y El-Aalamat D Popovic et al ldquoEvaluationof a panel of 28 biomarkers for the non-invasive diagnosis ofendometriosisrdquo Human Reproduction vol 27 no 9 pp 2698ndash2711 2012

[25] T DrsquoHooghe A Vodolazkaia C Kyama J M Mwenda and SSimoens ldquoHealth economics of endometriosisrdquo in Endometrio-sis L Rombauts J Tsaltas PMaher andDHealy Eds pp 1ndash16Blackwell Malden Mass USA 2008

[26] S Simoens G Dunselman C Dirksen et al ldquoThe burdenof endometriosis costs and quality of life of women withendometriosis and treated in referral centresrdquo Human Repro-duction vol 27 no 5 pp 1292ndash1299 2012

[27] N Luo J A Johnson JW ShawD Feeny and S J Coons ldquoSelf-reported health status of the general adult US population asassessed by the EQ-5D and health utilities indexrdquoMedical Carevol 43 no 11 pp 1078ndash1086 2005

[28] S Bernert A Fernandez J M Haro et al ldquoComparisonof different valuation methods for population health statusmeasured by the EQ-5D in three European Countriesrdquo Valuein Health vol 12 no 5 pp 750ndash758 2009

[29] M Thambisetty and S Lovestone ldquoBlood-based biomarkersof Alzheimers disease challenging but feasiblerdquo Biomarkers inMedicine vol 4 no 1 pp 65ndash79 2010

[30] E E-D R Othman D Hornung and A Al-Hendy ldquoBiomark-ers of endometriosisrdquo Expert Opinion on Medical Diagnosticsvol 2 no 7 pp 741ndash752 2008

[31] B W J Mol N Bayram J G Lijmer et al ldquoThe performance ofCA-125measurement in the detection of endometriosis ameta-analysisrdquo Fertility and Sterility vol 70 no 6 pp 1101ndash1108 1998

[32] R Socolov S Butureanu S Angioni et al ldquoThe value of serolog-ical markers in the diagnosis and prognosis of endometriosis aprospective case-control studyrdquo European Journal of ObstetricsGynecology and Reproductive Biology vol 154 no 2 pp 215ndash2172011

[33] M Mabrouk A Elmakky E Caramelli et al ldquoPerformance ofperipheral (serum and molecular) blood markers for diagnosisof endometriosisrdquo Archives of Gynecology and Obstetrics vol285 no 5 pp 1307ndash1312 2012

[34] A Tokmak M Ugur E Tonguc T var O Moraloglu and GOzaksit ldquoThe value of urocortin and Ca-125 in the diagnosis ofendometriomardquo Archives of Gynecology and Obstetrics vol 283no 5 pp 1075ndash1079 2011

[35] J PenninxM Brandes J P de Bruin PM Schneeberger andCJ C M Hamilton ldquoPrediction of pelvic pathology in subfertilewomen with combined Chlamydia antibody and CA-125 testsrdquoEuropean Journal of Obstetrics Gynecology and ReproductiveBiology vol 147 no 2 pp 178ndash182 2009

[36] A Mihalyi O Gevaert C M Kyama et al ldquoNon-invasive diag-nosis of endometriosis based on a combined analysis of sixplasma biomarkersrdquo Human Reproduction vol 25 no 3 pp654ndash664 2010

[37] F Nezhat ldquoReply of the Authors CA-125 as a biomarkerfor malignant transformation of endometriosisrdquo Fertility andSterility vol 91 no 5 article e36 2009

[38] R-H He W-M Yao L-Y Wu and Y-Y Mao ldquoHighlyelevated serum CA-125 levels in patients with non-malignantgynecological diseasesrdquo Archives of Gynecology and Obstetricsvol 283 supplement 1 pp 107ndash110 2011

[39] I M D L Ramos S Podgaec M S Abrao R de Oliveiraand E C Baracat ldquoEvaluation of CA-125 and soluble CD-23in patients with pelvic endometriosis a case-control studyrdquoRevista da Associacao Medica Brasileira vol 58 no 1 pp 26ndash32 2012

[40] A Agic S Djalali M M Wolfler G Halis K Diedrich and DHornung ldquoCombination of CCR1 mRNA MCP1 and CA125measurements in peripheral blood as a diagnostic test forendometriosisrdquoReproductive Sciences vol 15 no 9 pp 906ndash9112008

[41] E Ozhan A Kokcu K Yanik and M Gunaydin ldquoInvestiga-tion of diagnostic potentials of nine different biomarkers inendometriosisrdquo European Journal of Obstetrics amp Gynecologyand Reproductive Biology vol 178 pp 128ndash133 2014

[42] A TutenM KucurM Imamoglu et al ldquoCopeptin is associatedwith the severity of endometriosisrdquo Archives of Gynecology andObstetrics vol 290 no 1 pp 75ndash82 2014

[43] P Florio F M Reis P B Torres et al ldquoHigh serum follistatinlevels in women with ovarian endometriosisrdquo Human Repro-duction vol 24 no 10 pp 2600ndash2606 2009

[44] F M Reis S Luisi M S Abro et al ldquoDiagnostic value of serumactivin A and follistatin levels in women with peritoneal ovar-ian and deep infiltrating endometriosisrdquo Human Reproductionvol 27 no 5 pp 1445ndash1450 2012

[45] P G Signorile and A Baldi ldquoSerum biomarker for diagnosis ofendometriosisrdquo Journal of Cellular Physiology vol 229 no 11pp 1731ndash1735 2014

[46] A Drosdzol-Cop and V Skrzypulec-Plinta ldquoSelected cytokinesand glycodelin A levels in serum and peritoneal fluid in girlswith endometriosisrdquo Journal of Obstetrics and GynaecologyResearch vol 38 no 10 pp 1245ndash1253 2012

[47] V Kocbek K Vouk M D Mueller T L Rizner and NA Bersinger ldquoElevated glycodelin-A concentrations in serumand peritoneal fluid of women with ovarian endometriosisrdquoGynecological Endocrinology vol 29 no 5 pp 455ndash459 2013

[48] K Panoulis E Nieri G Kaparos et al ldquoThe presence of CD40CD40L and ADAM8 among endometriotic patientsrdquo MinervaGinecologica vol 63 no 2 pp 195ndash201 2011

[49] C G Andreoli V K Genro C A Souza et al ldquoT helper (Th)1Th2 and Th17 interleukin pathways in infertile patients withminimalmild endometriosisrdquo Fertility and Sterility vol 95 no8 pp 2477ndash2480 2011


[50] A Vodolazkaia X Bossuyt A Fassbender et al ldquoA highsensitivity assay is more accurate than a classical assay forthe measurement of plasma CRP levels in endometriosisrdquoReproductive Biology and Endocrinology vol 9 article 113 2011

[51] J Lermann A Mueller F Korber et al ldquoEvaluation ofhigh-sensitivity C-reactive protein in comparison with C-reactive protein as biochemical serum markers in women withendometriosisrdquo Fertility and Sterility vol 93 no 7 pp 2125ndash2129 2010

[52] A Drosdzol-Cop V Skrzypulec-Plinta and R Stojko ldquoSerumand peritoneal fluid immunological markers in adolescent girlswith chronic pelvic painrdquo Obstetrical and Gynecological Surveyvol 67 no 6 pp 374ndash381 2012

[53] A Tuten M Kucur M Imamoglu et al ldquoSerum YKL-40 levelsare altered in endometriosisrdquo Gynecological Endocrinology vol30 no 5 pp 381ndash384 2014

[54] G M Borrelli M S Abrao and S Mechsner ldquoCan chemokinesbe used as biomarkers for endometriosis A systematic reviewrdquoHuman Reproduction vol 29 no 2 pp 253ndash266 2014

[55] M M Wolfler I M Meinhold-Heerlein C Henkel et alldquoReduced hemopexin levels in peritoneal fluid of patients withendometriosisrdquoFertility and Sterility vol 100 no 3 pp 777ndash7812013

[56] F F Verit O Erel and N Celik ldquoSerum paraoxonase-1 activityin womenwith endometriosis and its relationshipwith the stageof the diseaserdquoHuman Reproduction vol 23 no 1 pp 100ndash1042008

[57] L Prieto J F Quesada O Cambero et al ldquoAnalysis of follicularfluid and serum markers of oxidative stress in women withinfertility related to endometriosisrdquo Fertility and Sterility vol98 no 1 pp 126ndash130 2012

[58] I Sharma L K Dhaliwal S C Saha S Sangwan and VDhawan ldquoRole of 8-iso-prostaglandin F2120572 and 25-hydroxycho-lesterol in the pathophysiology of endometriosisrdquo Fertility andSterility vol 94 no 1 pp 63ndash70 2010

[59] I V Lambrinoudaki A Augoulea G E Christodoulakos etal ldquoMeasurable serum markers of oxidative stress response inwomen with endometriosisrdquo Fertility and Sterility vol 91 no 1pp 46ndash50 2009

[60] F DrsquoAmico E Skarmoutsou G Quaderno et al ldquoExpressionand localisation of osteopontin and prominin-1 (CD133) inpatients with endometriosisrdquo International Journal of MolecularMedicine vol 31 no 5 pp 1011ndash1016 2013

[61] S H Cho Y S Ahn Y S Choi et al ldquoEndometrial osteopontinmRNA expression and plasma osteopontin levels are increasedin patients with endometriosisrdquoTheAmerican Journal of Repro-ductive Immunology vol 61 no 4 pp 286ndash293 2009

[62] G Matarese G de Placido Y Nikas and C Alviggi ldquoPatho-genesis of endometriosis natural immunity dysfunction orautoimmune diseaserdquo Trends in Molecular Medicine vol 9 no5 pp 223ndash228 2003

[63] H-F Huang L-H Hong Y Tan and J-Z Sheng ldquoMatrix met-alloproteinase 2 is associated with changes in steroid hormonesin the sera and peritoneal fluid of patients with endometriosisrdquoFertility and Sterility vol 81 no 5 pp 1235ndash1239 2004

[64] A K Singh R Chattopadhyay B Chakravarty and K Chaud-hury ldquoAltered circulating levels of matrix metalloproteinases 2and 9 and their inhibitors and effect of progesterone supple-mentation in women with endometriosis undergoing in vitrofertilizationrdquo Fertility and Sterility vol 100 no 1 pp 127e1ndash134e1 2013

[65] H Malvezzi V G Aguiar C C P de Paz J E Tanus-Santos IA de Araujo Penna and P A Navarro ldquoIncreased circulatingMMP-2 levels in infertile patients with moderate and severepelvic endometriosisrdquo Reproductive Sciences vol 20 no 5 pp557ndash562 2013

[66] P de Sanctis A Elmakky A Farina et al ldquoMatrixmetalloprote-inase-3 mRNA a promising peripheral blood marker for diag-nosis of endometriosisrdquoGynecologic andObstetric Investigationvol 71 no 2 pp 118ndash123 2011

[67] M Kianpour M Nematbakhsh S M Ahmadi et al ldquoSerumand peritoneal fluid levels of vascular endothelial growth factorin women with endometriosisrdquo International Journal of Fertilityand Sterility vol 7 no 2 pp 96ndash99 2013

[68] M L Mohamed M M El Behery and S A E-A MansourldquoComparative study between VEGF-A and CA-125 in diagnosisand follow-up of advanced endometriosis after conservativelaparoscopic surgeryrdquoArchives ofGynecology andObstetrics vol287 no 1 pp 77ndash82 2013

[69] V Bourlev N Iljasova L Adamyan A Larsson and M Olovs-son ldquoSigns of reduced angiogenic activity after surgical removalof deeply infiltrating endometriosisrdquo Fertility and Sterility vol94 no 1 pp 52ndash57 2010

[70] M Szubert J Suzin M Duechler A Szuławska M Czyzand K Kowalczyk-Amico ldquoEvaluation of selected angiogenicand inflammatory markers in endometriosis before and afterdanazol treatmentrdquo Reproduction Fertility and Developmentvol 26 no 3 pp 414ndash420 2014

[71] L Chen R Fan X Huang H Xu and X Zhang ldquoReducedlevels of serum pigment epithelium-derived factor in womenwith endometriosisrdquoReproductive Sciences vol 19 no 1 pp 64ndash69 2012

[72] L L Zong Y L Li and X Q Ha ldquoDetermination of HGFconcentration in serum and peritoneal fluid in women withendometriosisrdquo Di Yi Jun Yi Da Xue Xue Bao vol 23 no 8 pp757ndash760 2003

[73] K N Khan H Masuzaki A Fujishita et al ldquoPeritoneal fluidand serum levels of hepatocyte growth factor may predictthe activity of endometriosisrdquo Acta Obstetricia et GynecologicaScandinavica vol 85 no 4 pp 458ndash466 2006

[74] N KhoshdelRad Z Salehi F Mashayekhi O Abbasi and EMirzajani ldquoSoluble c-Met expression in the peritoneal fluidand serum of patients with different stages of endometriosisrdquoArchives of Gynecology and Obstetrics vol 289 no 5 pp 1107ndash1112 2014

[75] D K Shah K F Correia H R Harris and S A MissmerldquoPlasma adipokines and endometriosis risk a prospectivenested case-control investigation from theNursesrsquo Health StudyIIrdquo Human Reproduction vol 28 no 2 pp 315ndash321 2013

[76] N Pandey A Kriplani R K Yadav B T Lyngdoh and SC Mahapatra ldquoPeritoneal fluid leptin levels are increased butadiponectin levels are not changed in infertile patients withpelvic endometriosisrdquo Gynecological Endocrinology vol 26 no11 pp 843ndash849 2010

[77] M Nabeta Y Abe R Haraguchi K Kito Y Kusanagi and MIto ldquoSerum anti-PDIK1L autoantibody as a novel marker forendometriosisrdquo Fertility and Sterility vol 94 no 7 pp 2552ndash2557 2010

[78] M Nabeta Y Abe Y Takaoka Y Kusanagi and M ItoldquoIdentification of anti-syntaxin 5 autoantibody as a novel serummarker of endometriosisrdquo Journal of Reproductive Immunologyvol 91 no 1-2 pp 48ndash55 2011


[79] Y-C Yi S-C Wang C-C Chao C-L Su Y-L Lee and L-YChen ldquoEvaluation of serum autoantibody levels in the diagnosisof ovarian endometriomardquo Journal of Clinical Laboratory Anal-ysis vol 24 no 5 pp 357ndash362 2010

[80] R Gajbhiye A Sonawani S Khan et al ldquoIdentification andvalidation of novel serum markers for early diagnosis ofendometriosisrdquo Human Reproduction vol 27 no 2 pp 408ndash417 2012

[81] S Griffiths-Jones H K Saini S van Dongen and A JEnright ldquomiRBase tools for microRNA genomicsrdquo NucleicAcids Research vol 36 no 1 pp D154ndashD158 2008

[82] D P Bartel ldquoMicroRNAs target recognition and regulatoryfunctionsrdquo Cell vol 136 no 2 pp 215ndash233 2009

[83] K P Hoefig C Thorns A Roehle et al ldquoUnlocking pathologyarchives for microRNA-profilingrdquo Anticancer Research vol 28no 1 pp 119ndash123 2008

[84] K E Resnick H Alder J P Hagan D L Richardson CM Croce and D E Cohn ldquoThe detection of differentiallyexpressed microRNAs from the serum of ovarian cancerpatients using a novel real-time PCR platformrdquo GynecologicOncology vol 112 no 1 pp 55ndash59 2009

[85] A Fassbender O Dorien B de Moor and etal ldquoBiomarkers ofendometriosisrdquo in Pathogenesis and Treatment T Harada EdSpringer Berlin Germany 2014

[86] S-Z Jia Y Yang J Lang P Sun and J Leng ldquoPlasma miR-17-5p miR-20a and miR-22 are down-regulated in women withendometriosisrdquo Human Reproduction vol 28 no 2 pp 322ndash330 2013

[87] S Suryawanshi A M Vlad H-M Lin et al ldquoPlasma MicroR-NAs as novel biomarkers for endometriosis and endometriosis-associated ovarian cancerrdquo Clinical Cancer Research vol 19 no5 pp 1213ndash1224 2013

[88] W-T Wang Y-N Zhao B-W Han S-J Hong and Y-QChen ldquoCirculating microRNAs identified in a genome-wideserum microRNA expression analysis as noninvasive biomark-ers for endometriosisrdquo Journal of Clinical Endocrinology andMetabolism vol 98 no 1 pp 281ndash289 2013

[89] X Long P Jiang L Zhou and W Zhang ldquoEvaluation of novelserum biomarkers and the proteomic differences of endomet-riosis and adenomyosis using MALDI-TOF-MSrdquo Archives ofGynecology and Obstetrics vol 288 no 1 pp 201ndash205 2013

[90] N Zheng C Pan and W Liu ldquoNew serum biomarkers fordetection of endometriosis using matrix-assisted laser desorp-tionionization time-of-flight mass spectrometryrdquo Journal ofInternationalMedical Research vol 39 no 4 pp 1184ndash1192 2011

[91] A Fassbender E Waelkens N Verbeeck et al ldquoProteomicsanalysis of plasma for early diagnosis of endometriosisrdquoObstet-rics amp Gynecology vol 119 no 2 part 1 pp 276ndash285 2012

[92] K Khanaki M Nouri A M Ardekani et al ldquoEvaluation of therelationship between endometriosis and omega-3 and omega-6polyunsaturated fatty acidsrdquo Iranian Biomedical Journal vol 16no 1 pp 38ndash43 2012

[93] K Vouk N Hevir M Ribic-Pucelj et al ldquoDiscovery of phos-phatidylcholines and sphingomyelins as biomarkers for ovarianendometriosisrdquo Human Reproduction vol 27 no 10 pp 2955ndash2965 2012

[94] M Dutta M Joshi S Srivastava I Lodh B Chakravartyand K Chaudhury ldquoA metabonomics approach as a meansfor identification of potential biomarkers for early diagnosis ofendometriosisrdquo Molecular BioSystems vol 8 no 12 pp 3281ndash3287 2012

[95] R Zachariah S Schmid R Radpour et al ldquoCirculating cell-free DNA as a potential biomarker for minimal and mildendometriosisrdquo Reproductive BioMedicine Online vol 18 no 3pp 407ndash411 2009

[96] H Yang L Zhu S Wang J Lang and T Xu ldquoNoninvasivediagnosis of moderate to severe endometriosis the platelet-lymphocyte ratio cannot be a neoadjuvant biomarker forserum cancer antigen 125rdquo The Journal of Minimally InvasiveGynecology 2013

[97] J Olkowska-Truchanowicz K Bocian R B Maksym et alldquoCD4+ CD25+ FOXP3+ regulatory T cells in peripheral bloodand peritoneal fluid of patients with endometriosisrdquo HumanReproduction vol 28 no 1 pp 119ndash124 2013

[98] K E Webster S H Kennedy and C M Becker ldquoLevels ofcirculating angiogenic cells are not altered in women withendometriosisrdquoHumanReproduction vol 28 no 3 pp 651ndash6572013

[99] T L Rizner ldquoNoninvasive biomarkers of endometriosis mythor realityrdquo Expert Review of Molecular Diagnostics vol 14 no3 pp 365ndash385 2014

[100] V Thongboonkerd and P Malasit ldquoRenal and urinary pro-teomics current applications and challengesrdquo Proteomics vol5 no 4 pp 1033ndash1042 2005

[101] S H Cho Y J Oh A Nam et al ldquoEvaluation of serum andurinary angiogenic factors in patients with endometriosisrdquoTheAmerican Journal of Reproductive Immunology vol 58 no 6 pp497ndash504 2007

[102] N Tokushige R Markham B Crossett et al ldquoDiscovery of anovel biomarker in the urine in women with endometriosisrdquoFertility and Sterility vol 95 no 1 pp 46ndash49 2011

[103] L Kuessel A Jaeger-Lansky P Pateisky et al ldquoCytokeratin-19 as a biomarker in urine and in serum for the diagnosis ofendometriosismdasha prospective studyrdquoGynecological Endocrinol-ogy vol 30 no 1 pp 38ndash41 2014

[104] C M Becker G Louis A Exarhopoulos et al ldquoMatrixmetalloproteinases are elevated in the urine of patients withendometriosisrdquo Fertility and Sterility vol 94 no 6 pp 2343ndash2346 2010

[105] V Thongboonkerd ldquoPractical points in urinary proteomicsrdquoJournal of Proteome Research vol 6 no 10 pp 3881ndash3890 2007

[106] M M El-Kasti C Wright H K S Fye F Roseman B MKessler and C M Becker ldquoUrinary peptide profiling identifiesa panel of putative biomarkers for diagnosing and stagingendometriosisrdquo Fertility and Sterility vol 95 no 4 pp 1261e6ndash1266e6 2011

[107] S Cho Y S Choi S Y Yim et al ldquoUrinary vitamin D-bindingprotein is elevated in patients with endometriosisrdquo HumanReproduction vol 27 no 2 pp 515ndash522 2012

[108] B H Yun Y S Lee S J Chon et al ldquoEvaluation of ele-vated urinary enolase i levels in patients with endometriosisrdquoBiomarkers vol 19 no 1 pp 16ndash21 2014

[109] S Talbi A E Hamilton K C Vo et al ldquoMolecular pheno-typing of human endometrium distinguishes menstrual cyclephases and underlying biological processes in normo-ovulatorywomenrdquo Endocrinology vol 147 no 3 pp 1097ndash1121 2006

[110] G S Daftary and H S Taylor ldquoHydrosalpinx fluid diminishesendometrial cellHOXA10 expressionrdquoFertility and Sterility vol78 no 3 pp 577ndash580 2002

[111] J Kitawaki H Koshiba H Ishihara I Kusuki K Tsukamotoand H Honjo ldquoProgesterone induction of 17120573-hydroxysteroiddehydrogenase type 2 during the secretory phase occurs in the


endometrium of estrogen-dependent benign diseases but notin normal endometriumrdquo Journal of Clinical Endocrinology andMetabolism vol 85 no 9 pp 3292ndash3296 2000

[112] C P Fischer U Kayisili and H S Taylor ldquoHOXA10 expressionis decreased in endometrium of women with adenomyosisrdquoFertility and Sterility vol 95 no 3 pp 1133ndash1136 2011

[113] K E May J Villar S Kirtley S H Kennedy and C M BeckerldquoEndometrial alterations in endometriosis a systematic reviewof putative biomarkersrdquo Human Reproduction Update vol 17no 5 Article ID dmr013 pp 637ndash653 2011

[114] Y Absenger H Hess-Stumpp B Kreft et al ldquoCyr61 a deregu-lated gene in endometriosisrdquo Molecular Human Reproductionvol 10 no 6 pp 399ndash407 2004

[115] R O Burney S Talbi A E Hamilton et al ldquoGene expressionanalysis of endometrium reveals progesterone resistance andcandidate susceptibility genes in women with endometriosisrdquoEndocrinology vol 148 no 8 pp 3814ndash3826 2007

[116] L C Kao A Germeyer S Tulac et al ldquoExpression profiling ofendometrium from women with endometriosis reveals candi-date genes for disease-based implantation failure and infertilityrdquoEndocrinology vol 144 no 7 pp 2870ndash2881 2003

[117] J R A Sherwin A M Sharkey A Mihalyi P Simsa R DCatalano and T M DrsquoHooghe ldquoGlobal gene analysis of latesecretory phase eutopic endometrium does not provide thebasis for a minimally invasive test of endometriosisrdquo HumanReproduction vol 23 no 5 pp 1063ndash1068 2008

[118] J S Tamaresis J C Irwin G A Goldfien et al ldquoMolecularclassification of endometriosis and disease stage using high-dimensional genomic datardquo Endocrinology vol 155 no 12 pp4986ndash4999 2014

[119] S Kuokkanen B Chen L Ojalvo L Benard N Santoro andJ W Pollard ldquoGenomic profiling of microRNAs andmessengerRNAs reveals hormonal regulation in microRNA expression inhuman endometriumrdquo Biology of Reproduction vol 82 no 4pp 791ndash801 2010

[120] Q Pan X Luo T Toloubeydokhti andN Chegini ldquoThe expres-sion profile of micro-RNA in endometrium and endometriosisand the influence of ovarian steroids on their expressionrdquoMolecular Human Reproduction vol 13 no 11 pp 797ndash8062007

[121] E M C O Teague K H van der Hoek M B van der Hoek etal ldquoMicroRNA-regulated pathways associated with endometri-osisrdquoMolecular Endocrinology vol 23 no 2 pp 265ndash275 2009

[122] N Filigheddu I Gregnanin P E Porporato et al ldquoDiffer-ential expression of micrornas between eutopic and ectopicendometrium in ovarian endometriosisrdquo Journal of Biomedicineand Biotechnology vol 2010 Article ID 369549 29 pages 2010

[123] S M Hawkins C J Creighton D Y Han et al ldquoFunctionalmicroRNA involved in endometriosisrdquo Molecular Endocrinol-ogy vol 25 no 5 pp 821ndash832 2011

[124] A Braza-Boıls J Marı-Alexandre J Gilabert et al ldquoMicroRNAexpression profile in endometriosis its relation to angiogenesisand fibrinolytic factorsrdquoHuman Reproduction vol 29 no 5 pp978ndash988 2014

[125] R O Burney A E Hamilton L Aghajanova et al ldquoMicroRNAexpression profiling of eutopic secretory endometrium inwomen with versus without endometriosisrdquo Molecular HumanReproduction vol 15 no 10 pp 625ndash631 2009

[126] L Aghajanova and L C Giudice ldquoMolecular evidence for dif-ferences in endometrium in severe versus mild endometriosisrdquoReproductive Sciences vol 18 no 3 pp 229ndash251 2011

[127] R Petracco O Grechukhina S Popkhadze E Massasa YZhou and H S Taylor ldquoMicroRNA 135 regulates HOXA10expression in endometriosisrdquo Journal of Clinical Endocrinologyand Metabolism vol 96 no 12 pp E1925ndashE1933 2011

[128] T Toloubeydokhti Q Pan X LuoO Bukulmez andNChegin-i ldquoThe expression and ovarian steroid regulation of endometrialmicro-RNAsrdquo Reproductive Sciences vol 15 no 10 pp 993ndash1001 2008

[129] S Liu S Gao X Y Wang and D B Wang ldquoExpression ofmiR-126 and Crk in endometriosis MiR-126 may affect theprogression of endometriosis by regulating Crk expressionrdquoArchives of Gynecology and Obstetrics vol 285 no 4 pp 1065ndash1072 2012

[130] L Shen S Yang W Huang et al ldquoMicroRNA23a andMicroRNA23b deregulation derepresses SF-1 and upregulatesestrogen signaling in ovarian endometriosisrdquo Journal of ClinicalEndocrinology and Metabolism vol 98 no 4 pp 1575ndash15822013

[131] A Fassbender N Verbeeck D Brnigen et al ldquoCombinedmRNA microarray and proteomic analysis of eutopic endome-trium of women with and without endometriosisrdquo HumanReproduction vol 27 no 7 pp 2020ndash2029 2012

[132] L Wang W Zheng X-Y Ding J-K Yu W-Z Jiang and S-Z Zhang ldquoIdentification biomarkers of eutopic endometriumin endometriosis using artificial neural networks and proteinfingerprintingrdquo Fertility and Sterility vol 93 no 7 pp 2460ndash2462 2010

[133] C M Kyama D TrsquoJampens A Mihalyi et al ldquoProteinChiptechnology is a usefulmethod in the pathogenesis and diagnosisof endometriosis a preliminary studyrdquoFertility and Sterility vol86 no 1 pp 203ndash209 2006

[134] A Fassbender P Simsa C M Kyama et al ldquoTRIzol treatmentof secretory phase endometrium allows combined proteomicand mRNA microarray analysis of the same sample in womenwith and without endometriosisrdquo Reproductive Biology andEndocrinology vol 8 article 123 2010

[135] X Ding L Wang Y Ren and W Zheng ldquoDetection of mito-chondrial biomarkers in eutopic endometria of endometriosisusing surface-enhanced laser desorptionionization time-of-flight mass spectrometryrdquo Fertility and Sterility vol 94 no 7pp 2528ndash2530 2010

[136] C M Kyama A Mihalyi O Gevaert et al ldquoEvaluationof endometrial biomarkers for semi-invasive diagnosis ofendometriosisrdquo Fertility and Sterility vol 95 no 4 pp 1338e3ndash1343e3 2011

[137] S Tamburro M Canis E Albuisson P Dechelotte C Darchaand G Mage ldquoExpression of transforming growth factor 1205731in nerve fibers is related to dysmenorrhea and laparoscopicappearance of endometriotic implantsrdquo Fertility and Sterilityvol 80 no 5 pp 1131ndash1136 2003

[138] K J Berkley N Dmitrieva K S Curtis and R E Papka ldquoInner-vation of ectopic endometrium in a ratmodel of endometriosisrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 101 no 30 pp 11094ndash11098 2004

[139] N Tokushige R Markham P Russell and I S Fraser ldquoHighdensity of small nerve fibres in the functional layer of theendometrium in women with endometriosisrdquo Human Repro-duction vol 21 no 3 pp 782ndash787 2006

[140] M Al-Jefout G Dezarnaulds M Cooper et al ldquoDiagnosis ofendometriosis by detection of nerve fibres in an endometrialbiopsy a double blind studyrdquoHuman Reproduction vol 24 no12 pp 3019ndash3024 2009


[141] A Bokor C M Kyama L Vercruysse et al ldquoDensity of smalldiameter sensory nerve fibres in endometrium a semi-invasivediagnostic test for minimal to mild endometriosisrdquo HumanReproduction vol 24 no 12 pp 3025ndash3032 2009

[142] F Aghaey Meibody A Mehdizadeh Kashi A Zare Mirzaieet al ldquoDiagnosis of endometrial nerve fibers in women withendometriosisrdquo Archives of Gynecology and Obstetrics vol 284no 5 pp 1157ndash1162 2011

[143] C Leslie T Ma B McElhinney R Leake and C J Stewart ldquoIsthe detection of endometrial nerve fibers useful in the diagnosisof endometriosisrdquo The International Journal of GynecologicalPathology vol 32 no 2 pp 149ndash155 2013

[144] X Zhang B Lu X Huang H Xu C Zhou and J LinldquoInnervation of endometrium andmyometrium inwomenwithpainful adenomyosis and uterine fibroidsrdquo Fertility and Sterilityvol 94 no 2 pp 730ndash737 2010

[145] S Altmae F J Esteban A Stavreus-Evers et al ldquoGuidelines forthe design analysis and interpretation of rsquoomicsrsquo data focus onhuman endometriumrdquo Human Reproduction Update vol 20no 1 pp 12ndash28 2014

[146] A Fassbender N Rahmioglu A F Vitonis et al ldquoWorldEndometriosis Research Foundation Endometriosis Phenomeand Biobanking Harmonisation Project IV Tissue collectionprocessing and storage in endometriosis researchrdquo Fertility andSterility vol 102 no 5 pp 1244ndash1253 2014

[147] N Rahmioglu A Fassbender A F Vitonis et al ldquoWorldEndometriosis Research Foundation Endometriosis Phenomeand Biobanking Harmonization Project III fluid biospecimencollection processing and storage in endometriosis researchrdquoFertility and Sterility vol 102 no 5 pp 1233ndash1243 2014

[148] M Gion and A S Fabricio ldquoNew frontiers in tumor markerstudies from biobanking to collaboration in translationalresearchrdquo International Journal of BiologicalMarkers vol 26 no2 pp 73ndash74 2011

[149] C M Becker M R Laufer P Stratton et al ldquoWorld endo-metriosis research foundation endometriosis phenome andbiobanking harmonisation project I Surgical phenotype datacollection in endometriosis researchrdquo Fertility and Sterility vol102 no 5 pp 1213ndash1222 2014

[150] A F Vitonis K Vincent N Rahmioglu et al ldquoWorld endo-metriosis research foundation endometriosis phenome andbiobanking harmonization project II Clinical and covariatephenotype data collection in endometriosis researchrdquo Fertilityand Sterility vol 102 no 5 pp 1223ndash1232 2014

[151] E Sheldon K C Vo R A McIntire et al ldquoBiobanking humanendometrial tissue and blood specimens standard operatingprocedure and importance to reproductive biology research anddiagnostic developmentrdquo Fertility and Sterility vol 95 no 6 pp2120e12ndash2122e12 2011


minimally invasive diagnostic such as a blood or office-basedtest These include risks inherent to the procedure (organdamage hemorrhage infection and adhesion formation)as well as general anesthetic complications Also patientsneed to travel to a hospital or outpatient surgicenter withassociated financial costs to the patient and the healthcaresystem as well as prolonged time away fromwork and familyThe requirement for invasive surgery for the diagnosis ofperitoneal implants strongly contributes to an average latencyof 7ndash11 years from onset of symptoms to definitive diagnosis[3 11] This delay in diagnosis is due in part to presumptivetreatment of pain with oral contraceptives (OCPs) andnonsteroidal anti-inflammatory drugs (NSAIDs) as well asreluctance of physicians to refer women to gynecologists fordefinitive diagnosis reluctance of women to confront theirown pain for fear of a cancer diagnosis and dismissal of painespecially dysmenorrhea as a ldquonormalrdquo event [12] Delayeddiagnosis and treatment has significant consequences asendometriosis is more advanced in women whose diagnosticlaparoscopy is delayed supporting progression of diseaseover time [13] Indeed longitudinal placebo-controlled trialswith second look laparoscopy have demonstrated that 71ndash83 of untreated lesions will progress or remain stable overa 12-month period [14] At more advanced stages (stage III-IV of the revised American Fertility Society (rAFS) system)of endometriosis the severity of pelvic pain may lead tohysterectomy often with oophorectomy Endometriosis is thethird leading cause of hysterectomy in the United States [15]and increasing evidence exists for the malignant transforma-tion of ovarian endometriomas to ovarian cancer particularlythe clear cell and endometrioid subtypes [16]

In this review we describe and discuss the current statusof biomarkers of endometriosis in plasma urine and endo-metrium This review aims to encourage optimized studydesign data interpretation and validation considerations infuture biomarker development studies

2 Diagnostic Test for Endometriosis

Thegold standard for the diagnosis of peritoneal endometrio-sis has been visual inspection by laparoscopy followed byhistological confirmation [7] A noninvasive diagnostic testcould be developed for serum or plasma urine endometrialor menstrual fluid that can be recovered from the posteriorvaginal fornix and from the cervix during speculumexamina-tion [17 18] A semi-invasive test could be developed in peri-toneal fluid obtained after transvaginal ultrasound guidedaspiration or in endometrium obtained after transcervicalendometrial biopsy [17 18] The most important goal of thetest is that no women with endometriosis or other significantpelvic pathology are missed who might benefit from surgeryfor endometriosis-associated pain andor infertility [17ndash19]

To achieve this a test with a high sensitivity is neededwhich is the probability of a test being positive whenendometriosis is present At present such a test does not exist[17 20]

A noninvasive test for endometriosis would be use-ful for women with pelvic pain andor subfertility withnormal ultrasound This would include nearly all cases of

minimal-mild endometriosis some cases of moderate-severeendometriosis without clearly visible ovarian endometriomaand cases with pelvic adhesions andor other pelvic pathol-ogy who might benefit from surgery to improve pelvic painandor subfertility [17ndash19]

Although there is consensus in the World EndometriosisSociety that the development of a reliable noninvasive test isone of the top research priorities in endometriosis [11 21] thedevelopment of such a test from initial biomarker discoveryto a clinically approved biomarker assay is a long difficultand uncertain process [22] which can be classified in fourdifferent phases as described below [17 18]

Phase I (Preclinical Discovery Phase) This phase consists ofexploratory preclinical studies aiming to identify potentialbiomarkers In endometriosis research the state of the art inthis field has recently been reviewed by May et al [23]

Phase II (Retrospective Validation) This phase consists ofpreclinical assay development and validation of a clinicallyuseful noninvasive diagnostic test in the preclinical settingas has been done in the context of endometriosis in a recentpaper [24]

Phase III (Prospective Clinical Validation and Determinationof Clinical Utility)This phase establishes the diagnostic accu-racy and predictive value in the target population but thisphase has not yet been reached in endometriosis biomarkerresearch

Phase IV (Commercialization) Product development byindustry which has not yet been done successfully fornoninvasive endometriosis biomarkers

Overall most endometriosis biomarker studies haveremained at the level of Phase I [23] and only a few havemadeit to Phase II studies Clearly there is a need for well-designedPhase II and Phase III trials tomake progress in this field [18]A clinically reliable test for endometriosis can be expectedto have a profound impact on reduction of health care andindividual costs by [18]

(1) reducing time to diagnosis and the time wasted to seenumerous health care professionals

(2) subsequently reducing the time before individualizedspecialist care is invoked

(3) subsequently reducing expensive hit-and-miss treat-ments

(4) subsequently reducing expensive fertility treatmentsif the disease is under control before fertility isimpaired [25]

A worldwide study of costs caused by endometriosisindicates that the average annual total costs per woman are9579 euros of which 66 is caused by costs for productivityloss while medication counts for only 10 of the total yearlycosts [26] Furthermore endometriosis-associated symp-toms generated 0809 quality-adjusted life years per woman(the quality-adjusted life year is an outcome measure thataccounts for the quantity and quality of life and that allows for



3 Blood Biomarkers



31 Glycoproteins




























4 Urine Biomarkers































7 Conclusion



Disclosure




References
































































































































































3 Blood Biomarkers



31 Glycoproteins




























4 Urine Biomarkers































7 Conclusion



Disclosure




References

















































































































































































4 Urine Biomarkers































7 Conclusion



Disclosure




References



























































































































































































7 Conclusion



Disclosure




References






























































































































































update on biomarkers for the detection of endometriosis

Documents